Sometimes when he's bored, he kidnaps some micros to play, you don't hurt them and if they ask me, his soles are clean, he doesn't like dirt.
sticking micros to their sole or squeezing them feeling them twist.
He does it between his pecs too, it's almost like a massage for Jack when they squirm

Jack loves to play with humans, despite the enormous size jack can feel them

original: https://www.furaffinity.net/view/40760252/